Effect of Cyclic Solution Treatment on the Microstructure and Mechanical Properties of Maraging Steel

A new heat treatment process, presolid solution and cyclic solution treatment followed by aging treatment, is proposed to simultaneously increase the content of reversed austenite and precipitates in maraging steel. The optimized process significantly reduces the martensite block size from 798 to 705 nm, while increasing the content of reversed austenite from 18.2% to 29.6% and precipitates from 0.0328% to 0.0523%, compared to traditional methods. The cyclic solution treatment promotes multiple nondiffusive shear martensite transformations which increase the dislocation density and retained austenite, acting as nucleation sites for precipitates and reversed austenite, and also accelerating element partitioning during aging treatment. The multiscale microstructure, including high-density dislocation laths martensite, reversed austenite, and Ni₃Ti precipitates, contributes to achieving high yield strength (1193 MPa) and reasonable ductility (8.0%). This is mainly attributed to precipitation strengthening, the transformation-induced plasticity effect (TRIP) of reversed austenite during tensile testing, and the toughening effect of refined martensite lath.